如何通过子句动态订购

Question

我正在使用SQL Server 2008，我想根据输入列名和排序顺序（asc/desc）对数据进行排序。如何使以下查询动态？

DECLARE @iColumnName VARCHAR(24); 
DECLARE @iSortOrder VARCHAR(10); 

SET @iColumnName = 'ReceiptLocation'; -- ReceiptLocation/DeliverLocation/NominationNbr 
SET @iSortOrder = 'DESC'; -- DESC/ASC 

SELECT sum(NominationNbr) 
    ,sum(ReceiptLocation) 
    ,sum(DeliverLocation) 
FROM tables 
GROUP BY NominationNbr 
    ,ReceiptLocation 
    ,DeliverLocation 
ORDER BY CASE @iColumnName 
     WHEN 'ReceiptLocation' 
      THEN ReceiptLocation 
     WHEN 'DeliverLocation' 
      THEN DeliverLocation 
     ELSE NominationNbr 
     END 

     CASE @iSortOrder 
     WHEN 'DESC' 
      THEN DESC 
     ELSE ASC 
     END 

Answer 1

您需要将两者结合起来。我建议这个非常笨拙代码：

ORDER BY (CASE WHEN @iColumnName = 'ReceiptLocation' AND @iSortOrder = 'DESC' 
       THEN ReceiptLocation 
      END) DESC, 
     (CASE WHEN @iColumnName = 'ReceiptLocation' 
       THEN ReceiptLocation 
      END) ASC, 
     (CASE WHEN @iColumnName = 'DeliverLocation' AND @iSortOrder = 'DESC' 
       THEN DeliverLocation 
      END) DESC, 
     (CASE WHEN @iColumnName = 'DeliverLocation' 
       THEN DeliverLocation 
      END) ASC, 
     (CASE WHEN @iSortOrder = 'DESC' 
       THEN NominationNbr 
      END) DESC, 
     NominationNbr ASC 

每个CASE语句是一个独立的命令键。但是，如果它们不匹配，值为NULL，因此密钥在没有匹配时不会执行任何操作。

你也可以使用动态SQL来实现这一点。如果您有一个简单的查询和可用于ORDER BY的索引，那么这会更有效。